This invention relates to the manufacture of like-new golf balls wherein a portion of a discarded or reclaimed golf ball is used as the core of the like-new ball.
Conventional methods of manufacturing golf balls involve the steps. of first producing a cured elastomer core, followed by molding a durable dimpled cover around the core. The core itself may be formed from a solid and homogenous elastomer, which is cured in a spherical mold to provide a spherical core, for example, as disclosed in U.S. Pat. No. 5,072,944. Another type of core comprises an inner or central core filled with liquid, with the central core having an outer layer of elastomer windings, such as, for example, described in U.S. Pat. No. 4,943,332.
A dimpled cover is molded onto the core by one of two known methods. In the compression molding method, a pair of semispherical cover blanks or shells of polymer material are disposed around the core, and the assembly is placed in a mold comprising a pair of closeable mold halves defining a spherical dimpled cavity. The mold halves are compressed and heated, causing the cover material to become plastic and to be molded into a continuous dimpled cover around the core. Excess cover material escapes through sprues at the mold parting line. Both thermoplastic polymers, such as ionomers, and thermoforming elastomers such as synthetic rubbers, are used for this purpose. An early description of this process may be found in U.S. Pat. No. 2,787,024.
Another method of forming a cover of a golf ball is by injection molding. In this method, the core is first centered in the mold by retractable pins, and molten thermoplastic cover material is injected at high pressure around the cores to provide a cover. The mold is then cooled, and the balls are ejected from the mold.
After a golf ball has been in use for a period of time, the cover becomes scratched, deformed, or discolored, and the ball must be discarded. While some used golf balls may be cleaned and reused, it is estimated that many millions become too damaged each year and are discarded. Discarded golf balls are not biodegradable and therefore become a permanent part of the environment.